The present invention relates to a device and a method for supplying coating products to the atomizers of an installation for spraying coating products.
It is known to supply the atomizers of an installation for spraying coating products via product circulation conduits, also known as xe2x80x9ccirculatingsxe2x80x9d, from large-capacity tanks of products, whose capacity may attain several thousands of liters. Such tanks are generally located in storage premises at a distance from the spraying installations. Taking into account the usual distance between the store and the spraying installation, the products present in the circulatings during operation are of the order of several hundreds of liters, which renders it economically impossible to change products in such circulatings, as the quantities of products lost thereby are inacceptable. It is therefore necessary to provide one circulating per shade of colour used.
Now, the number of shades used in an installation for spraying coating products is tending to increase, which induces an increase in the number of circulating lines and increases the cost of the installation accordingly, while problems of space requirement are raised, particularly at the level of the passages through partitions.
The use of tanks borne on the arm of a multi-axis robot does not necessarily enable this problem to be solved. In effect, in the system known from EP-A-0 274 322, coating product circulatings are provided up to the zone of activity of the robot. In other systems, such as disclosed for example in EPA-0 796 665, a carrousel is provided for filling cartridges with coating products but circulatings for supplying coating products are provided up to the vicinity of this carrousel for filling the cartridges.
In all cases, the permanent stirring of the coating products in the circulatings leads to a degradation of their physico-chemical properties due to the mechanical stresses to which they are subjected, in particular the shear undergone at the level of the changes in direction, the pumps or the pressure regulators.
Another solution known from DE-A-197 04 573 consists in using prefilled cartridges, which are for example disposable, but this leads to complex manipulations of a large number of cartridges, which is not economically satisfactory and renders the system of management of such an installation considerably complex.
It is a particular object of the present invention to overcome these problems by proposing a novel atomizer supply device which does not necessitate the construction of a circulating up to the vicinity of an installation and avoids the manipulation of too large a number of cartridges.
To that end, the invention relates to a device for supplying coating products to the atomizers of an installation for spraying coating products on objects to be displaced by a conveyor, this device comprising at least one principal tank, adapted to supply secondary tanks each intended for an atomizer, at least one station for distributing the contents of the principal tank between the secondary tanks, and means for displacing the full secondary tanks towards application members adapted to displace the atomizers opposite the objects to be coated. Each secondary tank forms with the atomizer for which it is intended, a sub-assembly adapted to be displaced, by the afore-mentioned displacement means, between an application member and the distribution station, and vice versa.
The principal tank or tanks make it possible to supply different secondary tanks of the installation without the use of expensive and cumbersome circulatings. The principal tanks may be packaged outside the factory in which the installation is employed and, in particular, in the premises of the coating product manufacturer, the principal tanks in that case corresponding to a particular packaging of the product. It then suffices to transport different principal tanks up to the distribution station, which is installed near the spraying installation, then to transfer the contents of the principal tank into different secondary tanks which may then be conducted towards the application members which may be robots. The secondary tanks are used successively in the installation, which means that it is unnecessary to manage a large number of individual cartridges. Thanks to the connection of the secondary tanks and the atomizers, the sub-assemblies are displaced in unitary fashion between the application members and the distribution station in which the atomizers and the tanks can be cleaned before the secondary tanks are filled. This considerably simplifies the manipulations of the tanks and allows a good compactness of the elements mounted on the application members, for example at the level of the wrists of the multi-axis robots.
According to advantageous aspects of the invention, the device incorporates one or more of the following characteristics:
Units for temporary storage of the sub-assemblies are each arranged in the zone of activity of at least one application member. This makes it possible to conduct the sub-assemblies towards the application members, or from the latter in return towards the filling station, in masked time, independently of the cycle time of the application members.
The distribution station is located at the level of a median part of the installation, this station being connected by first displacement means to the application member(s) located upstream with respect thereto and in the direction of displacement of the sub-assemblies, and by second displacement means to the application member(s) located downstream. The positioning of the distribution station reduces the paths of displacement of the sub-assemblies, which consequently makes it possible to reduce the cycle times.
The or each principal tank is adapted to contain a quantity of coating product sufficient to supply the secondary tanks intended for the atomizers of the installation for completely coating an object or part of an object. In this way, a principal tank may for example make it possible to supply all the atomizers located on one side of the installation, or on half of such a side, with a suitable quantity of paint, without waste. In a variant, the quantity of product present in the principal tank corresponds to the complete coating of an object, the secondary tanks in that case being distributed between the application members or robots located on the two sides of the objects displaced by the conveyor.
The displacement means comprise at least one conveyor, adapted to displace the sub-assemblies from the distribution station up to the vicinity of the application members. This conveyor is associated with units for temporarily storing the sub-assemblies, these units each being disposed in the zone of activity of at least one application member. The temporary storage units make it possible to distribute the secondary tanks in masked time with respect to the phases of applications of coating product, the interruption of the spraying essentially corresponding to a change of tank and/or of sub-assembly comprising such a tank, for each application member, such as a robot. In a first embodiment, each unit comprises two locations for temporarily receiving sub-assemblies each incorporating a secondary tank, an application member being able to alternately deposit and remove such a sub-assembly in and out of these locations. In a second embodiment, two units are provided for each application member, first units being intended for the temporary storage of sub-assemblies each incorporating a secondary tank before their use by an application member, while second units are intended for temporary storage of such sub-assemblies after their use by an application member. In that case, the first and second temporary storage units may be connected to the distribution station by two different sections of the same conveyor or by two independent conveyors.
The distribution station comprises a carrousel on whose periphery the sub-assemblies may be disposed and at whose centre principal tanks may be disposed.
The invention also relates to a method which may be carried out with the device described hereinbefore and, more specificially, to a method which comprises the steps consisting in:
transferring a coating product from a principal tank into secondary tanks;
conducting the secondary tanks up to the vicinity of application members adapted to displace the atomizers opposite the objects to be coated, and
fixing the secondary tanks on the application members, method in which the secondary tanks are conducted in sub-assemblies each also comprising at least one atomizer associated with each secondary tank.
According to advantageous aspects of the invention, the method may comprise the following additional steps:
The sub-assemblies are temporarily stored in the vicinity of the application members in units provided to that end and each disposed in the zone of activity of at least one application member.
The principal tank is filled with a sufficient quantity of product for coating the same object or a part of the same object by different atomizers and the atomizers are supplied by means of secondary tanks filled by transfer from this principal tank.
Finally, the invention relates to an installation for spraying coating products comprising a device as described hereinabove, possibly employed with the aid of the method as described hereinabove. The cost price of such an installation is substantially less than the known installations having to be supplied with circulatings and it is much simpler to use than an installation supplied with cartridges each intended for an atomizer.